The present invention relates generally to machinery for manipulating electrodes and more particularly to devices and methods for joining graphite electrodes for use with metal arc furnaces.
Metal arc furnaces include large vessels for melting metal. Heat may be generated inside the furnaces using graphite electrodes across which electric current is passed. Heat is generated inside the furnace due to a high voltage arc formed by the current passing through one or more electrodes. The heat is used to melt metal.
During use, graphite electrodes are consumed within the furnace vessel, requiring electrodes to be replaced over time. As electrode material is consumed in the furnace, the electrode is shortened to a length where it is no longer independently usable. However, a partially-consumed electrode may be joined to a second partially-consumed or complete electrode to form a joined electrode that can be used. Thus, the partially-consumed electrode may still be useful when placed in combination with a second electrode portion.
Electrodes may be joined in an end-to-end configuration using a threaded joint in some applications. When electrodes are combined, electrical conductivity is generally maintained across the joint, and electricity may be passed from one electrode to the second in the joint electrode. A threaded joint is commonly used to join electrodes. The joining procedure requires at least one electrode to be rotated relative to a second electrode such that a threaded engagement occurs.
Conventional tools and methods for joining electrodes having a threaded joint include powered electrode joining devices including an electrode holder that is configured to grip the fixed electrode having a threaded socket, and a torque device that is configured to grip and spin the free electrode with a threaded rod onto the fixed electrode, the threaded rod engaging the threaded socket to join the electrodes.
Often times the threaded socket in the fixed electrode can contain dust, debris, or graphite residue, particularly when the fixed electrode is a used electrode which has been removed from an active furnace. Dust, debris, or graphite residue contained in the threaded socket of the fixed electrode can negatively affect the quality of the joint formed between the fixed electrode and the free electrode. For instance, having stray particles in the threaded socket can negatively affect the electrical connectivity between the used electrode and the free electrode, which can adversely affect the efficiency of the metal arc furnace when the electrodes are subsequently used in the furnace.
What is needed then are improvements in electrode joining apparatuses that can help remove dust and debris from a fixed electrode positioned in the electrode joining apparatus.